1. Field of the Invention
This invention relates generally to cardiac surgery. More specifically, this invention provides methods for enhancing the performance of cardiac surgery. In particular, this invention relates to systems and methods which use servo-mechanisms under surgeon control to augment a surgeon's ability to perform surgical procedures on a beating heart.
2. Description of the Prior Art
Coronary artery disease remains the leading cause of morbidity and mortality in Western societies. Coronary artery disease is manifested in a number of ways. For example, disease of the coronary arteries can lead to insufficient blood flow resulting in the discomfort and risks of angina and ischemia. In severe cases, acute blockage of coronary blood flow can result in myocardial infarction, leading to immediate death or damage to the myocardial tissue. A number of approaches have been developed for treating coronary artery disease. In less severe cases, it is often sufficient to treat the symptoms with pharmaceuticals and lifestyle modification to lessen the underlying causes of disease. In more severe cases, the coronary blockages can often be treated endovascularly using techniques such as balloon angioplasty, atherectomy, laser ablation, stents, hot tip probes, and the like. In cases where pharmaceutical treatment and/or endovascular approaches have failed, or are likely to fail, it is often necessary to perform a coronary artery bypass graft (CABG) procedure.
CABG procedures are commonly performed using open-heart techniques. Such techniques require that the patient's sternum be divided and the chest be spread apart to provide access to the heart. The patient is then placed on a heart/lung machine which oxygenates the patient's blood and pumps it through the circulatory system during the CABG procedure. After the patient is placed on cardiopulmonary bypass, drugs are administered to temporarily stop the patient's heart (cardioplegia) to allow the CABG procedure to be performed. In the CABG procedure, a source of arterial blood (graft) is connected to a coronary artery downstream from an occlusion thus bypassing the occlusion. The source of blood is often the left or right internal mammary artery, and the target coronary artery can be the left anterior descending artery or any other coronary artery which might be narrowed or occluded. Conventional open surgical procedures for performing coronary artery bypass grafting are described in Kirklin & Barratt Boyes', Cardiac Surgery, John Wiley & Sons, Inc., N.Y., 1993 (2nd Ed.), fully incorporated herein by reference as if repeated verbatim immediately hereinafter.
While very effective in many cases, the use of open surgery to perform coronary artery bypass grafting is highly traumatic to the patient. The procedure often requires immediate post-operative care in an intensive care unit, a total period of hospitalization of seven to ten days, and a recovery period that can be as long as six to eight weeks. Thus, minimally invasive medical techniques for performing CABG procedures and other cardiac surgery have recently been proposed.
Minimally invasive surgical techniques are generally aimed at reducing the amount of extraneous tissue which is damaged during diagnostic or surgical procedures, thereby reducing the patient's recovery time, discomfort, and deleterious side effects. The common feature of minimally invasive surgical techniques is that a surgeon can visualize a surgical worksite within the human body and pass specially designed surgical instruments through natural orifices or small incisions to the worksite to manipulate human tissues. Minimally invasive surgical techniques (MIS) include endoscopy, laparoscopy, thoracoscopy, arthroscopy, retroperitoneoscopy, pelviscopy, nephroscopy, cystoscopy, cisternoscopy, sinoscopy, hysteroscopy and urethroscopy.
MIS techniques for cardiac surgery avoid the need to divide the sternum and open a large incision in the patient's chest. Typically, MIS techniques access the thoracic cavity through one or more small ports placed between the patient's ribs. Some access techniques involve removing a rib to gain access to the thoracic cavity. Other access techniques involve making small incisions across the sternum or adjacent the sternum. The heart and coronary arteries are typically visualized directly through the port or visualized with the use of an endoscope, thoracoscope, surgical telescope or video camera, or the like. Conventional thoracoscopic techniques are described in Landrenea et al., Ann Thorac. Surg. 54:80 (1992) p. 807, fully incorporated herein by reference as if repeated verbatim immediately hereinafter. In addition, further description of MIS cardiac techniques is provided by U.S. Pat. No. 5,458,574, fully incorporated herein by reference thereto as if repeated verbatim immediately hereinafter.
MIS techniques are less traumatic than open-heart surgery techniques for performing coronary artery bypass grafts (CABG). The MIS techniques have the potential for decreasing morbidity and mortality, surgical cost, and recovery time, when compared to conventional open surgical coronary bypass procedures. However, one of the most significant causes of patient morbidity during a cardiac procedure is the need for cardioplegia and cardiopulmonary bypass. First, the heart-lung machine requires a large blood transfusion to prime the system. Second, the heart-lung machine causes damage to the blood cells and other blood constituents resulting typically in severe post-operative swelling in the patient. Finally, there is a danger that the heart cannot be restarted after the procedure.
Present MIS techniques for cardiac surgery do not obviate the need for cardiopulmonary bypass or cardioplegia. Indeed, the constraints imposed by small access ports and specialized surgical instruments increase the difficulty of the required surgery. Because the difficulty of the surgery is increased, the need for the heart to be stationary and thus the need for cardiopulmonary bypass and cardioplegia may also be increased.
Mechanically-assisted surgical systems have been developed which augment a surgeon's ability to perform surgery. Such systems include servo-assisted surgical manipulators which operate surgical instruments to manipulate human tissues at the surgical worksite. The surgical manipulators support and control the surgical instruments after they have been introduced directly into an open surgical site or through trocar sleeves, or the like, into a body cavity, such as the patient's abdomen. During the operation, each surgical manipulator typically can provide mechanical actuation and control of a variety of different surgical instruments, such as medical cameras, tissue graspers, needle drivers, and the like. These surgical instruments can typically perform various different functions, such as holding or driving a needle, grasping a blood vessel, dissecting tissue, and the like. The surgical manipulators are typically controlled by the surgeon at a remote operator control station. An overview of the state of the art in computer-assisted and servo-assisted surgical instruments can be found in Computer-Integrated Surgery: Technology and Clinical Applications (MIT Press, 1986), fully incorporated herein by reference as if repeated verbatim immediately hereinafter. Exemplary embodiments of systems for manipulating surgical instruments can be found in U.S. Pat. Nos. 5,402,801; 5,417,210; 5,524,180; 5,515,478; 5,817,084; and 5,808,665, all of which are fully incorporated herein by reference as if repeated verbatim immediately hereinafter.
It is an object of this invention to provide systems and methods which augment a surgeon's ability to perform cardiac surgery and minimally invasive cardiac surgery through the use of servo-mechanical surgical manipulators and without cardiopulmonary bypass or cardioplegia. It is a further object of this invention to provide systems and methods which augment a surgeon's control of surgical instruments so as to enhance the performance of beating-heart surgery using MIS techniques.
It is also an object of this invention to provide systems and methods for augmenting a surgeon's ability to perform cardiac surgery through the use of servo-mechanical surgical manipulators.
It is also an object of this invention to provide systems and methods for augmenting a surgeon's ability to perform minimally invasive cardiac surgery through the use of servo-mechanical surgical manipulators.
It is a further object of this invention to provide systems and methods for enabling a surgeon to perform cardiac surgery without cardiopulmonary bypass or cardioplegia.
It is another object of this invention to provide systems and methods for enabling a surgeon to perform minimally invasive cardiac surgery without cardiopulmonary bypass or cardioplegia.
It is also another object of this invention to augment a surgeon's control of surgical instruments so as to facilitate beating-heart surgery using MIS techniques by allowing a surgeon to utilize the same or a similar level of dexterity in the control of surgical instruments as is available using open-heart techniques.
It is a further object of this invention to provide apparatus and methods for tracking and controlling cardiac motion during cardiac surgery without cardioplegia.